For purposes of this application, the term glitch refers generally to a pulse having a width less than a predetermined width. For example, in triggering oscilloscopes, it is desired to determine whether certain unusual pulses are occurring in a particular signal other than data or other desired pulses. Such pulses typically would have a shorter duration than the data pulses.
A glitch detector circuit, such as the one provided by the present invention, senses each pulse in the data signal. When a pulse occurs which has a shorter duration than the data pulse, or a predetermined width which is less than the data pulse, an output signal is generated indicating the occurrence of the pulse. When used with an analog circuit, particularly an analog oscilloscope, this output signal is used to determine when to begin a sweep of the subject signal to obtain a display of the glitch. If the subject signal is being stored in digital form, the signal generated by the invention determines when the storing of information digitally may be terminated, and the digitally stored data displayed.
In certain applications, both positive and negative (bipolar) data pulses are used. However, even in some monopolar applications both positive and negative glitches occur in the signal. It is therefore desirable to detect both positive and negative going glitches.
Circuits presently exist which detect bipolar glitches as described. However, such circuits tend to be very complex and therefore more costly to manufacture.